The Transistor as Switch section shows setup. Also read the "Connecting a transistor from the output of an IC" for an explanation of what's going on. Heck, read the whole page and you'll be a lot smarter in the end

The current drawn by a laser pointer is very low so pretty much any N-channel transistor you have will work.

Something you might have to play with is finding the right photo-transistor; most are at best sensitivity in the IR region (look at the datasheet), but you can get ones that are sensitive in other bandwidths.

I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

The Transistor as Switch section shows setup. Also read the "Connecting a transistor from the output of an IC" for an explanation of what's going on. Heck, read the whole page and you'll be a lot smarter in the end

The current drawn by a laser pointer is very low so pretty much any N-channel transistor you have will work.

Why do I need to use a transistor? If the end result is still the laser being rapidly cycled then what's wrong with just using one of the digi out pins?

I've driven a cheap laser pointer using a transistor without issue. No problem switching it at 38KHz for use with an IR receiver.

Interesting. How sensitive are the IR receivers to the visible red spectrum of the cheap laser pointers?

That's a tough question to answer; given the nature of the coherent beams of lasers it should be sensitive at "any" distance. I quickly got a signal at ~12 meters distance (the longest clear span in my house) without tweaking the laser focus, frequency, or power and didn't take it any farther. My goal was only to build a laser tripwire and I wasn't attempting long distance communication.

(assuming the voltage is not more than the required amount for the laser)?

Hint:- it is.

If the laser wants 3v, then I just add the appropriate resistor right? Problem solved. Is there something I'm missing or is it not that simple? If I am missing something, why can't it be mentioned in one or 2 sentences? Like this, "That won't work because X, Y, Z"

That's a tough question to answer; given the nature of the coherent beams of lasers it should be sensitive at "any" distance. I quickly got a signal at ~12 meters distance (the longest clear span in my house) without tweaking the laser focus, frequency, or power and didn't take it any farther. My goal was only to build a laser tripwire and I wasn't attempting long distance communication.

Did you use a modular IR receiver like is used in typical home IR remote controlled electronics? If so, which particular one did you use?

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